1. Field of the Invention
This invention relates generally to custom dentures and, more particularly, to an improved method for the formation and manufacture of custom dentures from synthetic materials.
2. Prior Art
The increasing longevity of individual life spans throughout much of the world accompanied by a heightened awareness of the need to maintain the ability to masticate a variety of foods throughout the individual's lifetime in order to provide for his nutritional, bulk and fiber needs has generated an expanding market for dentures. Over the years a host of different devices and a number of various methods of making dentures from synthetic materials have been utilized.
The early dentures has no palates. Upper and lower plates were little more than narrow rims constructed of wood, ivory and hippopotamus tusks which were whittled and shaped to conform to the approximate contours of the upper and lower ridges of an oral cavity. Patterns of the mouth were made of paper and cloth and were used as guides for fitting. The dentures were held in place by springs arranged in such a fashion as to push the upper rims against the upper ridge and the lower rims against the lower ridge.
Around the beginning of the 19th Century, the art of making plaster casts was developed. Palates were added to the upper plate giving improved retention and function. In the middle of the 19th Century, a composition of amber, linseed oil, guttapercha and sulfur was developed for use as a denture base. However, even with this new material available, denture construction was still tedious and time consuming and, because of this, necessarily expensive. Only the wealthy few could afford the services of a dentist while those of modest means went without.
It was not until vulcanite was successfully developed for a denture base material and porcelein as a material for teeth that dentistry was established as a profession that could serve the needs of the majority of people. Although vulcanite was a remarkable denture material for its time, it left much to be desired asthetically. In an attempt to provide more natural looking dentures, a variety of thermoset and thermoplastic resins were tried and ultimately discarded. These resins included such materials as cellulose nitrate, cellulose acetate, phenol formaldehyde, glycols, caseins, and a great many other materials. As did the rubber materials, some of the plastic resins changed their color, became brittle, or generally lost their form. Finally, in 1933, the use of methyl methacrylate (acrylic) was introduced into the making of dentures and today dominates as the most widely used material in the manufacture of dentures.
Conventionally, dentures are made by first taking impressions of the patient's oral cavity. These impressions are then transported to a dental technician who must make molds and castings individually. Teeth must then be set into the molds in preparation for flasking. Next the flask, containing the molding material and teeth, are compressed under high pressure and cured in hot water tanks. The resulting set of dentures are then removed from the flask, cleaned of excess material and sent back to the dentist for ultimate delivery to the dentist. The dentist must then fit the newly made dentures to the patient making adjustments as required.
This conventional method of manufacturing dentures suffers from several disadvantages. First, the dentures must individually be detailed by dental technicians. Since the dental technician may be in a location remote from the area of the dentist's practice, there exists opportunity for distortions in the construction of the conventional denture since the technician has no knowledge of the peculiarities of the patient's mouth. Additionally, conventional dentures require several visits by the patient in order to develop and fit the dentures properly thus causing inconvenience to the patient and possibly added emotional discomfort. Finally, conventional dentures require from two to four hours of chair time depending upon the specific method being employed by the dentist which is in addition to the several hours of technician time thus adding to the overall cost of the dentures.